Toilet Retrofit Devices Introduction

Over the past 25 years, numerous retrofit devices for tank-type toilets have been developed, patented, and, in some cases, actively sold in the marketplace.  These devices usually fall into one of three categories:

(a) Water Displacement Products

Toilet discplacement bag 1A device designed to reduce the amount water available in the tank for completing the flush, e.g., a toilet “dam” or displacement object (a bag, brick or other item intended to displace a quantity of water in the tank).   Displacement products should be used ONLY in toilets with a rated flush volume of 3.5 gallons (13 litres) or above.  Use of these devices in lower volume toilets could seriously affect the flush performance of the fixture and could actually result in double-flushing, thus increasing water consumption!  Displacement products are considered to be very temporary solutions to a water shortage and have a limited physical lifetime.  (The preferred action would be the replacement of the entire water-wasting toilet fixture rather than the temporary “fix”.)

(b) Early-Closing Toilet Flapper

A second device often promoted in the past by water utilities is the early-closing toilet flapper.  In this case, the original equipment fully buoyant flapper is replaced by a flapper with reduced buoyancy.   The reduced buoyancy causes the flapper to close the flush valve before the tank is entirely evacuated of water, hence the term “early-closing”.  As a result, only a fraction of the water in the tank flows through the flush valve to the bowl before the flush valve closes.  Many 1.6-gpf (6.0 Lpf) toilets from the 1990s continued to use the high water capacity tanks from the 1980s (3.5 gpf -13 Lpf or more), but employed early-closing flappers to achieve the desired 1.6 gpf 6.0 Lpf) flush volume. 

When the early closing flappers were replaced with a fully buoyant flapper designed for a 3.5 gpf (13 Lpf) fixture, the flush volume could easily be increased by 100% or more!  This undesirable characteristic led to the development in 2000 of the Los Angeles Supplementary Purchase Specification (SPS) by the water industry and which limited such adjustability.

Early-closing flappers, either as an original trim item in a toilet fixture or as an after-market product for retrofit, are not favored by the water utilities, due to the adjustability (in a new product) and poor flush performance that can result from their use (as a retrofit product).  In the latter instance, poor performance frequently results in double-flushing, which can significantly increase water use.

(c) Dual-Flush Conversion Devices

The third category of device is a more recent development.  The introduction to North America (in 1999) of the dual-flush toilet stimulated many 'inventors' and companies to develop their own products that converted a single-flush toilets to a dual-flush mode.  Two types of replacement products are available:  a replacement flush valve for gravity-fed toilets and a replacement handle for flushometer valve fixtures.   These products generally do not reduce the flush volume of the full flush (1.6 gpf, 3.5 gpf, = 6.0 Lpf or 13 Lpf or some other volume), but rather add the ability to use a reduced volume for liquids only.  In most cases, the reduced volume is 50-70% of the volume of the full flush.

To retrofit an existing single-flush gravity-fed fixture, nearly all of the products require the removal of the existing flush valve and replacement with the dual-flush valve.  There are many different products available for this purpose, but few have been independently tested to determine their effect upon flush performance.  (All, however, should be required to meet the compliance requirements of the ANSI standard ASME A112.19.10 in order to be approved for use in the U.S.).

In the case of flushometer valve fixtures, three products exist in the marketplace that provide for a simple conversion of the valve to dual-flush operation: Sloan Uppercut ( and Zurn AquaVantage AV (  Both of these products require to user to lift up on the handle for the reduced flush, and push down on the handle for a full flush.  A third product from Advanced Modern Technologies Corporation ( reverses the direction by activating the reduced flush with a downward action.  Each of the conversion products reduces the flush volume for a liquid-only flush by approximately 30%.

Water utilities should be concerned with the ability of retrofitted fixtures to adequately perform on the reduced flush, given that the fixture was not originally intended for that purpose.  Issues of customer dissatisfaction could arise over the failure to fully exchange all of the water in the bowl when the reduced flush is activated and, for gravity-fed fixtures, the ability of the device to refill the bowl with the correct amount of water.  Furthermore, real world savings resulting from the retrofitting with such devices (which can be quite costly) have not been fully established, nor has the actual cost-effectiveness of such a retrofit.